1. Field of the Invention
The present invention relates to a vehicular active drive assist system which assists a driver in driving by properly generating a warning when there is a possibility that own vehicle runs deviating from a traffic lane.
2. Description of the Related Art
A comprehensive active drive assist system (ADA system) which actively assists a driver in driving operations has been developed in recent years in order to improve safety of vehicle. This ADA system estimates the possibility of various incidences, such as a collision with a vehicle running ahead, contact with an object and deviation from a traffic lane, from information on vehicle driving environments or running state of own vehicle and, when it is predicted that safety can not be maintained, alerts the driver or otherwise performs control operation.
While a laser radar system, for instance, has conventionally been known as a device for obtaining the aforementioned vehicle driving environment information, Japanese Patent Laid-Open No. 265547/1993 covering an application filed by the present applicant proposes an approach to obtain three-dimensional recognition of a road and traffic environments with practically sufficient accuracy and promptness by processing information on images of scenery and objects ahead of the vehicle captured by a plurality of cameras installed onboard.
Prevention of deviation from a traffic lane, one of functions of the aforementioned ADA system, is intended to alert the driver to an extremely close approach to or crossing of a lane marker line by producing a warning, for instance, should such a situation occur, and thereby help prevent traffic accidents which might be caused by a lack of attention, dozing, failure to watch ahead, or other behavior related to the driver""s carelessness. Various proposals have already been made with respect to this lane deviation preventing function.
In the aforementioned lane deviation preventing function, warning to a driver is generally given in the form of the lighting or blinking of a warning lamp, the sounding of a warning buzzer or a chime, or voice, for example. Especially when the driver deviates from a traffic lane due to dozing, for instance, it is desirable that the warning be given continually by such warning unit. On the other hand, once the driver recognizes potential deviation from the traffic lane, the driver usually maneuvers his or her vehicle in a direction to prevent deviation from the traffic lane and, therefore, it may occasionally be undesirable to keep the warning activated after the driver has recognized the potential deviation from the traffic lane, because the driver could find it rather noisy or annoying.
The invention has been made in consideration of the foregoing circumstances. Accordingly, it is an object of the invention to provide an easy-to-use vehicular active drive assist system which can continue to give a warning against the presence of a possibility of deviation of own vehicle from a traffic lane to such an extent that a driver would not find the warning noisy or annoying.
To achieve the aforementioned object, a vehicular active drive according to the invention comprises a lane deviation judgment unit which judges the possibility of deviation of own vehicle from a traffic lane on a roadway ahead, and a warning control unit which activates a warning generating unit when the own vehicle is judged to have the possibility of deviation from the traffic lane, wherein the warning control unit activates the warning generating unit at preset time intervals as long as the judgment persists after the own vehicle has been judged to have the possibility of deviation from the traffic lane. As a result, it is possible to repeatedly produce a warning against the deviation from the traffic lane to such an extent that a driver would not find the warning noisy or annoying.
In the vehicular active drive assist system of the invention, the lane deviation judgment unit distinctively judges the possibility of deviation to the left and right directions of the traffic lane, and if the own vehicle is judged to have the possibility of deviation from the traffic lane in one of its left and right directions after once having been judged to have the possibility of deviation from the traffic lane in. the opposite direction, the warning control unit immediately activates the warning generating unit regardless of the time interval counted for the opposite direction. For example, if the possibility of deviation to the right of the traffic lane arises while the warning generating unit is being activated and producing the warning due to the presence of the possibility of deviation to the left of the traffic lane, the warning generating unit is immediately activated and the warning is generated. Therefore, it is possible to properly warn the driver of the possibility of deviation from the traffic lane again to assist the driver in driving even when the driver suddenly manipulates a steering wheel to avoid deviation from the traffic lane.
Further, in the vehicular active drive assist system of the invention, wherein the lane deviation judgment unit distinctively judges the possibility of deviation to the left and right directions of the traffic lane, and if the own vehicle is judged to have no possibility of deviation from the traffic lane after once having been judged to have the possibility of deviation in one of its left and right directions, and is judged again to have the possibility of deviation from the traffic lane in the same direction, the warning control unit immediately activates the warning generating unit regardless of the time interval initially counted for that direction. For example, if the possibility of deviation to the left of the traffic lane once disappears while the warning generating unit is being activated and producing the warning due to the presence of the possibility of deviation to the left of the traffic lane and the possibility of deviation to the left of the traffic lane arises again, the warning generating unit is activated and the warning is generated immediately. Therefore, even when the driver once takes action to avoid deviation from the traffic lane and then repeats the same steering action, it is possible to properly warn the driver of the possibility of deviation from the traffic lane again to assist the driver in driving.